Dive Brief:
- Researchers continue to struggle with determining what exposure level of listeria contamination leads to severe illness in consumers, according to new research from the Centers for Disease Control and Prevention (CDC).
- In recent years, widespread low-level listeria outbreaks have sickened only a handful of highly-susceptible consumers, the CDC found.
- Challenges researchers face include "the lack of an appropriate animal model, the relative rarity of outbreaks, long incubation periods that impede the collection of well-preserved implicated food samples, and heterogeneity of the initial contamination level," according to the report.
Dive Insight:
Blue Bell's listeria outbreak early last year provided fodder for the CDC researchers' report. The CDC's research is critical to helping both researchers and food and beverage companies understand how listeria contamination works. This is important particularly because low-level contamination may be more rampant than producers realize, even though low-level contaminations may never surface as an illness outbreak.
The ice cream manufacturer is in the midst of another listeria-based recall for its cookie dough ice cream now. Evidence of low-level contamination surfaced in the initial confusion between Blue Bell and its cookie dough supplier, Aspen Hills. Aspen Hills initially reported that the cookie dough tested negative for such a contamination before the product left its facility, but Blue Bell said it found the ingredient was already contaminated upon delivery.
Since then, Aspen Hills has enacted and expanded its cookie dough recall to other companies without ever revealing its list of customers. Lower-level listeria contamination may have prevented or decreased the impact of this recall earlier on.